This set of Human Physiology Multiple Choice Questions & Answers (MCQs) focuses on “Breathing and Exchange of Gases – Respiration Mechanism, Pulmonary Air Volumes & Lung Capacities”.
1. Oxygen is carried by __________
a) Platelets
b) Leucocytes
c) Erythrocytes
d) Monocytes
View Answer
Explanation: During respiration, the oxygen is carried by erythrocytes. It is also known as RBC’s.
2. In glycolysis during oxidation electrons are removed by __________
a) NAD+
b) ATP
c) Molecular oxygen
d) Glyceraldehyde-3-phoshate
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Explanation: Glycolysis is a metabolic pathway that converts glucose into pyruvate. During oxidation electrons are removed by NAD+. The energy released in this process is used to form ATP and NADH.
3. RQ of fat is ____________
a) one
b) more than one
c) less than one
d) infinity
View Answer
Explanation: RQ of fat is less than one. Fats require extra oxygen for the formation of H2O. It is around 0.7. For carbohydrate RQ is one.
4. How much percent of CO2 is expired?
a) 7%
b) 32%
c) 25%
d) 20%
View Answer
Explanation: During respiration CO2 is exhaled out from the body. 32% of CO2 is expired out.
5. When CO2 concentration in blood increased breathing becomes ____________
a) shallower and deeper
b) slow and deep
c) faster and deeper
d) no effect on breathing
View Answer
Explanation: When CO2 concentration in the blood increased breathing becomes faster and deeper. This happens due to the increase of carbon dioxide and breathing rate becomes faster.
6. The oxygen toxicity is related to _________
a) Blood poisoning
b) Failure of ventilation of lungs
c) Collapsing of the alveolar wall
d) Improper functioning of alveoli
View Answer
Explanation: The result of breathing increased partial pressure of oxygen is hyperoxia an excess of oxygen in body tissues. Oxygen toxicity is concern for underwater divers.
7. Carbon dioxide cannot be transported with hemoglobin.
a) True
b) False
View Answer
Explanation: Hemoglobin carries some of body’s respiratory carbon dioxide as carbaminohemoglobin, in which CO2 is bound to globin protein.
8. After deep inspiration maximum expiration of lungs is called ________
a) Vital capacity
b) Total lung capacity
c) Inspiratory capacity
d) Functional residual capacity
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Explanation: Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inhalation. A person’s vital capacity can be measured by a wet or regular spirometer.
9. Pulmonary ventilation movements are due to __________
a) Costal muscles and diaphragm
b) Diaphragm
c) Wall of lungs
d) Costal muscles
View Answer
Explanation: Pulmonary ventilation is commonly referred to as breathing. Air flows because of the pressure difference between the atmosphere and the gases inside the lungs. Costal muscles and diaphragm helps pulmonary ventilation.
10. If RQ is 0.6 in a respiratory metabolism it would mean that _________
a) Carbohydrate is used as respiratory substrate
b) Organic acids are used as respiratory substrate
c) Oxidation of respiratory substrate consumed more O2 than CO2 produced
d) Reaction is anaerobic
View Answer
Explanation: RQ is respiratory quotient. If RQ is 0.6 then Oxidation of respiratory substrate consumed more O2 than CO2 produced.
11. Partial pressure of oxygen in lungs is ____________
a) 60 mm Hg
b) 40 mm Hg
c) 110 mm Hg
d) 100 mm Hg
View Answer
Explanation: In a mixture of gases partial pressure is a pressure of that gas if it alone occupied the entire volume of the original mixture at the same temperature. Partial pressure of oxygen in lungs is 100 mm Hg.
12. Vital capacity of lung is __________
a) TV+IRV+ERV
b) TV+IRV+RV
c) TV+ERV
d) IRV+ERV
View Answer
Explanation: Vital capacity of lung is the sum of tidal volume, inspiratory reserve and expiratory reserve volume. IRV is about 1900-3300ml and ERV is700-1200ml.
13. Hamburger shift is also known as ___________
a) Bicarbonate shift
b) Chloride shift
c) Potassium shift
d) Sodium shift
View Answer
Explanation: Hamburger shift is a process which offers in a cardiovascular system and refers to the exchange of bicarbonate and chloride across the membrane of RBC. It is also known as the chloride shift.
14. Amount of CO2 in expired air is _________
a) 0.04%
b) 0.03%
c) 3.6%
d) 21%
View Answer
Explanation: The average human excels about2.3 pounds of carbon dioxide on a average day. Nearly 4% of carbon dioxide is present in exhaled air.
15. Dead space air in man is __________
a) 500ml
b) 150ml
c) 250ml
d) 1.5l
View Answer
Explanation: Dead space is the volume of air that is inhaled that does not take part in gas exchange because it remains in the conducting airways or it reaches alveoli that are not perfused or poorly perfused.
16. Total lung capacity is _____________
a) 5000-6000ml
b) 2500-5000ml
c) 4000-5500ml
d) 3000-6000ml
View Answer
Explanation: The average lung capacity of an adult human is about 6l of air. The tidal volume is the volume of air that is inhaled or exhaled in a single breath.
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